Why use metal deactivators in Lubricants?

Currently, metal deactivators are primarily classified into three main types: benzotriazole, triazole, and thiadiazole.

       Benzotriazole                                                                     1,3,4-Thiadiazole                                                  Triazole derivatives

Controlling the corrosive effects of active sulfur

Metal deactivators can both inhibit copper corrosion and improve the oxidation stability of oils, and they have been widely used. In recent years, both domestically and internationally, attention has been paid to transformer copper winding failures caused by corrosive sulfur. Corrosive sulfur reacts with copper to form cuprous sulfide (Cu2S), which deposits on the insulation paper and degrades its insulating properties, eventually leading to inter-turn insulation breakdown. Indeed, the East China Power Grid discovered transformer failures caused by corrosive sulfur. For oil-cooled drive motors, the lubricant inevitably comes into contact with various copper or copper-alloy electrical components inside the motor, which requires the oil to provide even superior copper corrosion protection.

Chours TA-30 is an ashless, oil-soluble corrosion inhibitor and metal deactivator, particularly effective for nonferrous metals, especially copper.

Controlling the catalytic oxidation of lubricants by metal surfaces

During use, lubricants inevitably undergo oxidation. If the oil contains trace amounts of metals-such as copper or iron ions-they act as catalysts that accelerate oxidation. Metal deactivators function by either forming chelates with metal ions or creating a protective barrier film on metal surfaces, thereby preventing metals from catalyzing the oxidation of oil.

The oxidation stability of lubricants is important and directly dictates both oil service life and equipment safety. When lubricants contact metals during transport or operation, or when metal ions are present in the oil, oxidation is accelerated-leading to the formation of acids, sludge, and deposits. Acids cause corrosion and wear on metal components, while sludge and deposits thicken the oil, leading to piston ring sticking and oil passageway blockages, which eventually degrade performance. Consequently, preventing metal ions from promoting oxidation is critical for lubricants.

What is a Metal Deactivator?

Metal deactivators (also known as metal passivators) are additives that prevent metals from reacting with petroleum products such as fuel oils and lubricants. They retard the rate of oxidation by passivating metals or metal ions and primarily consist of nitrogen-containing heterocyclic compounds, such as benzotriazole derivatives and thiadiazole derivatives.

Metal deactivators are widely used in automotive and industrial lubricants, such as gasoline engine oils, gear oils, internal combustion engine oils, and anti-wear hydraulic oils. They not only enhance the anti-oxidation and anti-corrosion performance of oils by passivating metal ions, but also exhibit a certain degree of friction-reducing and anti-wear effects.

For instance, the application of metal deactivators in gear oils is to inhibit oil oxidation and prevent (especially copper). By forming an inert protective film on metal surfaces, they block the catalytic effect of metal ions on oil oxidation, thereby substantially improving the oxidation stability of gear oils and extending the service life of both the oil and the equipment. This is indispensable for protecting copper alloy components (such as synchronizers and bearings) in gearboxes.

Chorus is a professional manufacturer of lubricant additives, offering metal deactivators and antioxidant packages tailored to diverse application scenarios, with same-day, latest price quotes available.